Automatic and semiautomatic telephone system



D. A. CHRISTIAN AUTOMATIC ma 'SEMIAUTOMATIC wsmrrnom: SYSTEM Filed Sept. '7, 1923 4 SheetsShe et l Oct. 13 .1925.

' D. A. CHRISTIAN AUTOMATIC AND SEMIAUTOMATIOJFTELEPKONE SYSTEM 4 Sheets-Sheet 2 Filed Sept. 7, 1923 Flglfcont) A Gin a W7 D. A. CHRISTIAN AUTOMATIC- AND SEMIAUTOMATIC TELEPHONE SYSTEM Filed Sept. '7. 192s 4 sheetksman Fig.2

Oct- 13,1925- D. A.= .CHRISTIAN AUTOMATIC AND SEMIAUTOMATIC TELEPHONE SYSTEM Filed Sept. 7, 1923 Fig.2. (cont) 4 Sheets-Sheet 4 uumanr r j wmmP lad/077w? Patented Got. 13, 1925.

UNITED STATES 1,556,98'? PATENT OFFICE";

DAVID ADAM CHRISTIAN, OF LONDON, ENGLAND, ASSIGNOR TO SIEMENS BROTHERS 8: COMPANY, LIMITED, OF LONDON, ENGLAND, A BRITISH COMPANY.

AUTOMATIC AND SEMIAUTOMA'IIO TELEPHONE SYSTEM.

Application filed September 7, 1923.

To all whom it may concern:

Be it lrnown that l, ill-win ADAM Unmo- TIAN, a British subject, residing at London, England, have invented certain new and use ful Improvements Relating to Automatic and Semiautomatic Telephone Systems, of which the following is a specification.

The present invention has reference to improvements in automatic telephone systems.

It has mainly in View arrangements for enabling a selector to successively hunt over more than one level to find a free or marked line. One case where such arrangements are desirable is that of a final selector where lines to the same private branch exchange are situated. in two or more adjacent levels and the final selector is to give access to a tree line of the group leading to the private branch exchange.

The selector used in the present invention is provided with means i'or causing release as regards rotary motion only.

On reaching predetermined contacts in the first level unsuccessfully searched over, release as regards rotary motion takes place and the selector wipers are then stepped up opposite to the next level and searching takes place over that level. It no tree line is found there and lines oi? the group are provided in the next level, the process is repeated. On reaching the last line of the group and it being found busy a busy signal may begiven in the usual manner. The predetermined contacts referred to may be extra contacts beyonr the usual ten sets in a level, or maybe the contacts immediately following the last contacts of the grouped lines situated in a level or some other suitable arrangement.

The accompanying diagrammatic drawing shows circuit arrangements according to the invention. tor a selector having separate vertical and rotary release detents as shown in British patent specification No. 136,497, and having an additional release magnet which operates solely on the rotary release detent.

Fig. 1 oi the drawing shows circuit arrangements 'for a final selector having a group of P. B. X. lines assigned to the same subscriber and occupying several levels of the selector.

Fig. 9. of the drawing shows circuit arrangements for a group selector, whereby, it all "the links outgi'iing from a given level are engaged, the selector wipers after traversing Serial NO. 661,427.

the level, are released as regards the rotary movement and return to the position they occupied just before being stepped into the level and are then automatically stepped up opposite the next higher level and enter the same.

Reference will now be had to Fig. l'in which relays shown as having rectangles en closing the windings are slow release relaysj Two additional relays Pt) and PT are provided to assist in the carrying out of the invention. Furthermore the selector is provided with a double extra wiper having arms 10 and 11 of which 10 trails behind arm 11 so as to make contact with adjacent contacts of contact are 12. There is an arc of contacts 12 for each level containingl. 15. X. lines and each contact oi: the arc corresponding to a P. B. X. line is connected to earth with the exception ot the contact corresponding to the last line of the group of P. B. IX. lines.

A very convenient arrangement for the provision ol' contacts 12 is. one in which a hall cylinder of metal is fitted on the selector above and in front of the ordinary bank of contacts. The half cylinder has one hundred tapped and drilled holes in which screws are inserted as required to form contacts 12. The holes are situated so as to correspond in position with the bank contacts. The addi tional wipers are adapted to make contact with the said screws.

The vertical magnet is denoted by H, the rotary magnet by R, the main release magnet which withdraws both vertical and rotary release detents by M, and the rotary release magnet which acts only on the rotary release detent by M Relay PR controls the circuit for the searching for atree P. B. X. line. All contacts are shown in the unoperated position, contacts of relay A have a reference letter (4 followed by a sufiix number and similarly for other relays, contacts which are operated by the wiper spindle on lilting from normal are denoted by the letter In and a sultix; contacts which operate when the wiper spindle rotates from normal position are indicated by the letter w and. a sutfix.

The circuit operations are as tollo\vs: When the final selector is seized, relay N is energized in a circuit from earth over battery, winding 1, contact 70 test wire 0 and to ground over the test relay of the preceding selector. Relay N prepares a holding circuit over its winding 2 and contact a which is shunted until contact lc opens on the first movement of the selector. Contacts n a and a are closed or CllzlIlgii'Otl over in a manner obvious from the drawing.

The impulse relay A is energized, on the seizure of the selector, in a circuit from ground over contact p6 of relay PT, winding of relay A, back contact 251 of relay TR, back contact i of test relay T, bacl contact 8 of ring relay S, and over the 6 line to battery at the preceding selector.

Thereupon slow acting relay D is energized in a circuit from ground over battery. contact a, winding of relay D, back contact pt front contact a ()fill01lll2tl contact off-normal contact to to earth. Relay D prepares the circuit of the vertical magnet H at front contact (Z and prepares a holding circuit for itself over contact (P, the initiating circuit being broken at contact 711 on the first movement of the wiper spindle. Relay D also at contact d opens a point in a circuit for relay G. The subscriber operating his number dial causes relay A to beat and on each de-energization of relay A the vertical magnet H is energized in a circuit from earth over vertical magnet H, back contact of relay G, back contact ((1, front contact (Z to battery and earth. The selector wipers are stepped up to the required level and slow release relay D which is be ing held over its contact (Z and the repeated closure of the circuit over 'ack contact a relapses on the termination of the train of impulses.

On the falling back of relay D, a circuit for relay G is closed, the circuit being from earth over battery, contact a winding of relay G which is slow acting, back contact pr back contact al back contact 195 contact 703 which changed over on the first vertical step, contact 10 to earth. Relay changes over, at its contact 9 the magnet operating circuit from the vertical to the rotary magnet and prepares a holding circuit for itself at front contact It also closes a circuit for relay D at contact 9', the circuit being from earth, battery, closed contact 92 winding of relay D, back conta pt, front contact a closed contact 9", contact 10 to earth. Relay D energizes and completes the holding circuit for relay 6- at contact (Z Relay D, as before, prepares its own holding circuit at (5 and the magnet operating circuit at contact (Z On receipt of the first of the train of impulses, relay A falls back and the rotary magnet R receives current from earth over battery, front contact (Z back contact c front contact 9 rotary magnet to earth. The wipers are moved one step and contact 20 opens leaving slow release relay D dependent for holding current on the circuit over the back contact a At the end of a train of impulses, relay D releases since relay A is held energized. Relay D on release, breaks the holding circuit of relay G which falls back slowly. On the release of relay D the line called, is tested over the following circuit :earth, battery, back contact (Z of relay D, closed contact 9 windings 1 and 2 of relay T, closed contact 11 C arm of the final selector and over the test contact and wire to the called line. if the called line is free relay T energizes and closes a holding circuit for itself over contact t and its low resistance winding 2. Relay G by this time falls back and opens the initial testing circuit at contact Relay T at front contacts 2 and 25" connects the a and b speaking leads th ough to the a and b wipers of the selector. ltelay G having fallen back a circuit is then made at contact g for the ring relay S, the circuit being from earth over battery, winding of relay 3, back contact a (relay A de-energizcs on the change over of contact 6 back contact tr, back contact 798 contact 10 in its o'fi -normal position, contact g to earth. Relay S energizes and interrupted ringing current from leads 13 and 14 is fed into the line to the subscribers instrument over front contacts 8 and s Vinding l of the ring trip relay TR is in series with the lead I l. {)11 the reply of the called subscriber relay TR is energized by direct current over the subscribers loop, and at its frontcontact tr, short circuits relay S and brings in the holding winding 2 of relay TR by opening the short circuit across it into the previously described circuit for relay S. Relay S deenergizing closes over its back contacts a and s the circuit through from the calling to the called subscriber. The release magnet circuit of the selector is kept open at contacts a and L. The holding circuit of relay T is controlled by relay N at contact 71 and on the termination of the call by the calling subscriber hanging up his receiver results in the de-energization of relay N with the consequent release of the final selector.

The sequence of operations described would apply in the case of an ordinary line or the first line of a l. B. X. group if free.

In the case of a busy ordinary line relay T would not operate so that relay it remains connected to the B lead over back cont-act t. On the falling back of relay a circuit is made for winding 2 of relay TR as follows; earth, contact contact 10 back contact as winding 2 of relay TR, front contact a? (which short circuits relay resistance, to battery. Relay energizes and connects a busy tone circuit over wires 15 and 16 and contacts ti and tr to the calling subscriber.

If the first line of the P. B. :1. group were not free, the following sequence of operations would occur. Relay T does not energize on the fall back of contact d so that relay PR has time to energize in a circuit from earth over battery, back contact 25 front contact 71 closed contact d of relay D, resistance, wiper 11 and the earthed con tact of are 12. Relay PR energizing opens contact 1W and thereby prevents a short circuit of its winding when on the next step wiper arm 10 reached the first earthed contact of are 12 which corresponds to the rirst B. P. X. line. Relay PR also at contact 1W closes a circuit from earth over battery, interrupter 15, contact 727 front contact a front contact g rotary magnet It to earth; relay (1* being held against release on the falling back of contact al by the change over of contact 191". The rotary magnet consequently steps the wipers round over the P. B. X. lines, relay T testing each line over the circuit from earth, battery, back contact 6?, closed contact (Z windings 1 and 2 of relay T, closed contact a to the test wiper CL On a tree line being found relay T operates, and at contact t opens the circuit of relay PR. Relay PR relapsing opens the rotary magnet circuit at contact 321 The ringing and other operations proceed as before.

If all the P. B. X. lines on the level be engaged, the means for releasing the selector in a rotary direction and the stepping up to the next level come into operation.

These means include in the present case, relays PT and PS with the necessary circuits.

The provision of the additional wiper 10 and the short circuiting contact 391 of relay PR is to meet the case where it is required that a line of the P. B. X. group shall. be treated as an ordinary line on the number of that line being dialled in the first instance by the subscriber. This is a convenience when say at night the P. B. X. is unattended and incoming calls are passed throu h to "a. certain extension.

If the number of any line of the P. B. X. group excepting the first line of the group as regards each level is dialled by the subscriber relay PR is short circuited across the wipers 10 and 11 and contact pr so that it connot operate and theoperations occurring on testing the line are the same as in the case or a call to an ordinary line.

Winding l of relay PS is connected to an eleventh contact in the test bank and when the test wiper leaves the tenth test contact on finding the associated P. B. X. line busy, relay T and relay PS energizes on reaching the eleventh contact. llelay T at its contact opens the circuit of relay PH and the latter by its release opens the rotary magnet circuit at contact 79 1. The release oi? relay PR also results in the opening of the holding circuit of relay G at contact ,W and relay releases.

PS beingenergized contact ps is changed over and relay PT is energized in series with winding 2 (Fill relay PS in' the following circuit :-earth, battery, closed contact a winding of relay PT, winding 2 of relay PS, front contact 228 rotary oft normal contact U22, closed contact g earth. Relay PT energizes and at contact pt opens the circuit of relay T and the initiating circuit of relay PS. On relay T falling back the circuit otthe rotary release magnet llil." is closed, the circuit being from earth ()VQ! battery, back contact 29, contact (closed when relay PS energized) magnet winding M to earth.

The wipers now return to the position they originally reached when the wip spindle was stepped up by the vertical net. The spindle rotary oil-normal contr 10 is restored to its normal position a breaks the circuit of relays PS and PT, but relay PT is held over its contact pt contact @12 and contact 9 Ptelay PS releases slowly and since contact 101 is now closed relay D is meanwhile energized in a circuit from earth over battery, vlosed contact a winding of relay D, ii ront contact pi front contact 298 of relay PS, contact in its off-normal position, contact w to earth. Relay D energizes and since the circuit oi relay A was previously broken at contact 2015 the circuit of the vertical magnet H is closed over contact (Z of relay l), the circuit being ground over battery, iront contact (Z back contact a back contact 9 magnet H, to earth, and the wipers are stepped up opposite the next level. Relay D releases slowly on the opening of contact ps A circuit is now available for the energization of relay G being as follows :earth, battery, contact 7%, winding of G, back contact pr back contact (Z back contact ps oilnornial contact 70 closed contact 10 to earth. Relay G on energization prepares the circuit of the rotary magnet R at 9 and by the closure of contact 9 causes the energization of relay D in a circuit from earth over battery, contact a winding of relay D, front contact 1025 contact 9 contact ca to earth.

The rotary magnet circuit is completed at contact d and the wipers are given one step w 1SQUPOI1 the circuit of relay D is broken at 20*. Meanwhile the holding circuit of relay PT has been opened at contact and. on the slow fall back of relay PT being complete, relay A is re-energized over contact 7915 Relay A opens the existing circuit of the rotary inagnetht at contact a and connects the rotary magnet over front ccntact at to front contract 297 @perations now proceed in a manner before described. It the line on which the wipers rest is free, relay T responds and the called line is rung. If the line is busy, relay PR energizes and the rotary magnet Ill is operated over the circuit including contact 21 It will be seen that PS initiates the release of the wipers and the stepping up to the next level. If the group of l. B. X. lines covers only two levels the wipers after now hunting unsuccessfully over the level do not encounter a CllQUl't to a relay PS on the eleventh contact and there any suitable arrangement may be provided for giving a busy signal.

It should also be noted that a relay PS need not necessarily be connected to the eleventh contact, but may be connected to the test contact succeed'. g the test contact of the last line of the P. ll. X. lines situated in that level.

Fig. 9 shows a case of a group selector arranged for successive hunting over two or more levels.

Referring to 2 on the seizure of the group selector, impulse relay fl. energizes in a circuit from earth, over contact 778 of r y the winding of relay A. back contact t of relay T. the B lead battery at the precedir switch.

Relay A energizes and at contact a closes a circuit for slow release relay D as followsearth, battery, winning of relay D, vertical off-normal contact Z1 front con tact 0. the C lead to earth at the preceding switch.

Relay D at contact (Z prepares a circuit for the vertical magnet H. On the first inipulse being received. relay A releases and over its back contact (2- closes the circuit the v0 vi nr aet H, the circuit being from earth over contact of relay T, front contact (Z contact a". the vertical magnet to cart-lied battery. The wipers are given one vertical step whereupon the off-normal :ts operate. T the changeover of contact Z3 relay D is held during the train of inu'iulses over contact 712 front contact a and back contact a of relay A. Battery over resistance and contact 15 is also disconnected on the first vertical step, from the incoming tes lead: this effects no change as the test relay of the preceding switch is assumed to be held in a local circuit and to apply earth to the C wiper of that switch.

At the end of the train of impulses, relay A is held energized and the holding circuit of relay D is broken at back contact a Relay D releases, and at its back contact a closes the circuit of the rotary magnet, the circuit being from earth, over battery, interrupter 18. rotary magnet R, front contact a closed contact 117 back contact (Z contact to earth. The wipers are stepped round in search of a free link, and on reaching the same, relay T energizes in a circuit from battery at the succeeding switch, the incoming test lead, bank contact and C wiper of the group selector, winding 2 of relay T, front contact a ofrelay A, the C- lead to earth at the preceding switch. Engaged links have earths on their C bank contacts, relay T energizing closes a locking circuit for itself over contact t the circuit being from earth over battery, contact pt, wtrling i of relay T to the C lead. At contact a earth is applied to the C wiper to mark the link engaged. At front contacts 2 and t the A and B leads are connected through to the wipers; at contact If the circuit of the rotary magnet is broken. Relay .3. has its circuit broken at back contact 25 a releases disconnecting winding 2 of re- T from the C lead.

If however all the ten links in the level are engaged the wipers are stepped onto the eleventh bank contacts. A circuit is then made as follows, earth, over battery, contact p25 winding 2 of relay PS, the eleventh b ank contact, the C wiper, winding 2 of relay front contact; a to the earthed C a lead. Relays T and PS operate. Relay T ener ized, connects 1ts winding 1 to the incoming 0 line over contact t, at contact i the circuit of the rotary magnet is broken. Relay A is also disconnected at back con tact t Relay PS by closing contact 798 makes the following circuit: earth over battery, back contact (Z winding '1 of relay PS. winding of relay PT, front contact 198 to earth. At contact 728 the circuit of the main release magnet is opened and at contact ps another point in the circuit of relay A. is opened.

lVhen relay PT operates a circuit for relay D is prepared over contact pt At contact 7925 the circuit of the holding winding 1 of relay T is opened and at contact 2925 the circuit of operating winding- 2 of relay PS and operating winding 2 of relay T is opened. Relay T releases and contact 15 falling back, the circuit of the rotary release magnet M is now made from earth over contact 23 back contact d contact pt, rotary off-normal contact 20 rotary release magnet v 1 to battery.

The selector then; releases as regards rotary movement. lVhen the wipers have re turned to the position they occupy before rotary n'iovement, the ofBnormal contacts 20 are back at normal. The closure of contact "1.0 results in the energization of relay D in a. circuit from earth over battery, winding of relay D, contact in the oft-normal position, contact 10 front contact pt to earth. Relay D operates and is held over contact (Z back contact a and the 0 line. At contact 6Z2 the circuit of the vertical magnet H is made and the wipers are consequently raised one step to the next level. At contact 01 the circuit of relays PS and PT is opened and these relays release. Contact 323 falls back and the circuit of relay A is made, relay T having previously fallen back. The change-over of contact a causes the release of relay D. The selector rotary magnet now receives current in a circuit from earthed battery over interrupter l8, rotary magnet, front contact a contact it, back contact (Z contact 6 to earth and the selector wipers now search for a free link.

If the group 01 lines covers more than two levels relay PS is connected to the eleventh contact of each level with the exception of the last. The eleventh contact of the last level may be connected to battery so that relay '1 operates and stops the wipers on the eleventh contacts. A. busy tone circuit connected to eleventh A and B bank contacts could then give a busy signal to the calling subscriber.

What I claim as my invention and de sire to secure by Letters Patent is 2- 1. In a telephone system a selector having two directional motion, wipers which execute a first movement and a second movement, means for causing release as regards the second movement on a predetermined contact being reached in that movement and for returning the wipers to the starting position for that movement and means automatically operating for re-starting the first movement on the return of the wipers.

2. In a telephone system a selector having two directional movement, wipers which execute a vertical movement followed by a rotary movement. means for causing release as regards the rotary movement on a predetermined contact being reached in that movement and for returning the wipers to the starting position for that movement and means automatically operating for re -starting the vertical movement on the return of the wipers.

In a telephone svstem a selector having two directional motion. winers which eXecute a vertical movement followed by a rotary movement, a rotary release magnet, means For operating said magnet on a pre determined contact being reached in the rotary movement and means automatically operating for restarting the vertical movement on the return of the wipers to the starting position for the rotary movement.

4. In a telephone system a selector havinn; two directional motion, wipers which execute a first movement and a second movement, means for stopping the second movement on a predetermined contact being reached, in that movement, means for then causing release as regards the second movement and the return of the wipers to the starting position for that movement and means automatically operating for restarting the first movement on the return of the said wipers. H

5. Ina telephone system a selector having two directional motion, Wipers which exe ing two directional motion, wipers which IXecute a first movement and a second movement, at first relay which on the Wipers reaching a predetermined contact in the second movement causes a cessation of the second movement, means for then causing re lease as regards the second movement and for returning the wipers to the starting position for that movement, a second relay which controls the circuit of the first relay and means automatically operating for restarting the first movement on the return of the wipers.

7. In a telephone system a selector having two directional motion, wipers which execute a first movement and a second movement, a release controlling device for causing release as regards the second movement, means for stopping the second movement of the wipers on reaching a predetermined contact in that movement, a relay controlling the circuit of said release controlling device, means for causing the operation of said I'e-. lay on said predetermined contact being reached and means automatically operating for restarting the first movement on the return of said wipers to the starting position for the second movement.

8. In a telephone system a selector having two directional motion, wipers which exeonto a first movement and a second movement, a release device for causing release as regards the second movement, means for stopping the second movement of the wipers on reaching a predetermined contact in that movement, a relay exercising control over the operation of the said release controlling device which relay operates on said predetermined contact being reached, a further relay controlled by said relay said further relay controlling the means for stopping the second movement ofthe wipers and means automatically operating for re-starting the first movement on the return of the wipers to the starting position for the second movement.

9. In a telephone system a selector having two directional movement, wipers, means for causing a first movement of the said wipers, means for causing a second movement of the said wipers, a release controlling device for causing release as regards the second movement, means for causing the operation of said release controlling device on a predetermined contact being reached in that movement and means automatically operating for temporarily bringing into action the means causing the first movement of the said wipers after the return of the wipers to the starting position for the second movement.

10. In a telephone system a selector having two directional motion, wipers, means for causing a first movement of the said wipers, means for causing a second movement of said wipers, a release controlling device for causing release as regards the second movement, means for causing the operation of said release controlling device on a predetermined contact being reached in the second movement, means automatically operating for temporarily closing the circuit energizing the means causing the first movement of the wipers on the return of the wipers to the starting position for the second movement, and shaft contacts controlling the means for temporarily closing the circuit.

11. In a telephone system a selector having two directional motion wipers, means for causing a first movement of the said wipers, means for causing a second movement of said wipers, a release controlling 'device for causing release as regards the second movement, means for causing the operation of the said release controlling device on a predetermined contact being reached in the second movement and means for temporarily closing the circ'uit energizing the means causing the first movement comprising a slow release relay controlling said means and shaft contacts opening the circuit of the said slow release relay on the return of the wipers after reaching the said predetermined contact.

12. In a telephone system a selector having two directional motion, wipers, means for causing a first movement of the said wipers, a release controlling device for causing release as regards the second movement, means for causing the operation of the said release controlling device on a predeter mined contact being reached in the second movement and means for temporarily closing the circuit energizing the means causing the first movement comprising a relay controlling the circuit. of the said means, a second relay for preparing a circuit for said relay, a slow release relay for further preparing a circuit for said first relay, shaft contacts for opening the circuit of the said slow release relay and for closing the cir cuit of the first relay, said shaft contacts operatingon the return of the wipers after reaching the said predetermined contacts.

13. In a telephone system a selector having two directional motion, wipers, a magnet for causing a first movement of the said wipers, a magnet for causing a second movement of the said wipers, a release magnet for causing release as regards the second movement, a test relay for stopping the second movement on reaching a predetermined contact in that movement, a second relay energized on the wipers reaching said predetermined contact and which exercises control on the circ'uit of the said release magnet, a third relay for opening the circuit of said test relay and means for temporarily closing the circuit of the magnet causing the first movement afterthe wipers have returned, said means comprising a relay controlling the circuit of said magnet, the said third relay, and shaft contacts.

l l. In a telephone system a selector having two directional motion, wipers which execute a first movement and a second movement, a release controlling device for causing release as regards the second movement, means for causing the operation of said release controlling device on the wipers reaching a predetermined contact in the second movement, means for restarting the first movement on the return of the wipers and means for subsequently starting the second movement.

In atelephone system a selector having two directional motion, wipers which execute a vertical movement and a rotary movement a release controlling device for causing release as regards rotary movement means for causing the operation of said release controlling device on the wipers reaching a predetermined contact in the rotary movement, means for re-starting the vertical movement on the return of the wipers and means for subsequently starting the rotary movement.

16. In a telephone system a selector hav-- ing two directional motion wipers which execute a vertical movement and a rotary movement, a release controlling device for ca'using release as regards rotary movement, means for operating said release controlling device on reaching a predetermined contact in the rotary movement, means for causing a vertical movementof the wipers on their return, means for preparing a circuit for energizing the means causing rotary movement of the wipers and means for complet-r ing said circuit. 7 r

17. In a telephone system a selector having two directional motion, wipers which execute a vertical movement and a rotary movement, a release controlling device for causing release as regards rotary movement, means for operating said release controlling device on reaching a predetermined contact in the rotary movement,ineans for causing a vertical movement of the wipers on their return, a slow release relay, a second relay the circuit of which is closed on the release of the said slow release relay said second relay preparing a circuit for energizing the inn Ill)

means causing rotary motion of the wipers.

18. In a telephone system a selector having two directional motion, wipers which execute a vertical movement and a rotary movement, a release controlling device for causing release as regards rotary movement means for operating said release controlling device on reaching a predetermined contact in the rotary movement, means for causing a vertical movement of the wipers on their return, a slow release relay, a second relay the circuit or which is closed on the release of the said slow release relay, said second relay preparing a circuit for energizing the means causing the rotary movement of the wipers, a third relay for completing said circuit and means for temporarily energizing said third relay.

19. In a telephone system a selector having two directional motion wipers which execute a vertical movement followed by a rotary movement a release controlling device for causing release as regards rotary movement, a test relay for stopping the rotary movement of the wipers on reaching a predetermined contact in that movement aslow release relay for controlling the circuit of the said test relay, means for causing the operation of the release controlling device onthe predetermined contact being reached, means for causing a vertical movement of the wipers on the return of the wipers, a second slow release relay, a further relay the circuit of which is closed on the release of the first slow release relay said further relay preparing a circuit for energizing the means for causing rotary movement of the wipers, a third relay for completing the circuit for energizing the said means an energizing circuit for said third relay controlled by the first slow release relay and said further relay.

20. In a telephone system a selector having two directional movement, wipers which execute a first movement and a second movement, means for causing said movements, an impulse relay controlling over a contact thereof a circuit for energizing the means for causing said movements, means for causing the release as regards the second movement ot the wipers on reaching a predetermined contact in that movement means for thereon causing the de-energization of said impulse relay means for temporarily closing a circuit for energizing the means for causing a first movement of the wipers and means for subsequently closing a circuit for energizing the means for causing a second movement of the wipers.

21. In a telephone system a selector having two directional motion, wipers which execute a first movement and a second movement, means for causing said movements an impulse relay controlling over a contact thereof a circuit for energizing the means for causing said movements first and second slow release relays controlling release as regards the second movement when a predetermined contact is reached in that movement, means controlled by the first slow release relay for temporarily energizing on the return of? the wipers the means causing the first movement, a further relay and means controlled by said further relay for energizing the means causing the second movement of the wipers.

22, In a telephone system a selector having two directional motion, wipers which execute a first movement and a second move ment, means for causing said movements, an impulse relay controlling over a contact thereof a circuit for energizing the means for causing said movements first and second slow release relays controlling release as regards the second movement when a predetermined contact is reached in that movement, means controlled by the first and second slow release relays for temporarily energizing on the return of the wipers, the means causing the first movement of the wipers, a further relay and means controlled by said further relay and the second slow release relay for energizing the means causing the second movement of the wipers.

In testimony whereof I afiix my signature.

DAVID ADAM CHRISTIAN. 

